1. Field of the Invention
The present invention relates to a magnetic recording medium comprising a magnetic metallic iron particles. More particularly, it relates to a magnetic recording tape having excellent orientation.
2. Description of the Prior Arts
It is well known that the important characteristics of magnetic particles for magnetic recording include a coercive force of magnetic particles, a dispersibility of magnetic particles in a magnetic paint for coating and an orientation of magnetic particles in a magnetic recording tape. As it is well known, these characteristics are important factors which highly affect to the characteristics of the magnetic recording tape. The shape of the magnetic particle directly relates to these characteristics of the magnetic particles. For example, when the coercive force is given by the shape anisotropy as the conventional magnetic recording medium, the coercive force is increased depending upon the improvement of the acicular property of the particles. The dispersibility is improved by decreasing branched or curved particles whereby the steric hindrance is decreased to improve the orientation and accordingly, the recording characteristics of the magnetic recording tape are improved. Therefore, it is important to obtain a magnetic particle having excellent acicular property with smaller branched configuration in the preparation of the magnetic particles for a magnetic recording medium. in the industrial process, hydrated ferric oxide which is mainly goethite .alpha.-FeOOH and easily forms an acicular particle is firstly produced as a starting material and is converted into a magnetic metallic iron particle by heating, dehydrating and reducing it. These process have been usually employed.
In this process, the acicular property of the resulting particles depends on the shape of the starting goethite and accordingly, the shape of the goethite particles should be controlled. But in the conventional type of the particles, the deformation and sintering of the particles are disadvantageously easy to occur by the dehydration and the migration of atoms in the reduction process. This causes the limitation of the orientation in the tape as described below.
The present invention is to overcome the disadvantages and to succeed in the invention of the magnetic recording tape which is different from the conventional one.